Oil Radiator - results do not seem right

Hi Everyone!
I need some help on my oil cooling radiator analysis.

I am machining an aluminum radiator for cooling a lubricating oil and I want to run a conjugate heat transfer analysis to figure out if the radiator is properly designed to cool the fluid.

Conditions:

  • Radiator will be machined out of 6061 Aluminum
  • Oil input temperature will be 60c
  • Radiator has heat sink fins on one side
  • Radiator will have no fan (operating in open outdoors)
  • Ambient air temperature will be 30c

Purpose of this analysis:
I need to machine a radiator in this form factor that can cool the fluid down to 40c given a constant outdoor temperature of 30c. The radiator relies on a heat sink and natural air convection. I would like to perform this analysis so I can optimise the machined radiator design.

Issues with results:

  • My simulation results are showing an exit fluid temperature of 30c with an ambient temp of 30c. That would be impossible. Usually in my experience we can get radiators within about 10c of ambient temperature.
  • In the simulation view it seems that the fluid is getting cold way too fast and the gradient only lasts a couple of cores rather than a gradient over the whole radiator.
  • On the temperature curve it shows the fluid temp only increasing, then the analysis stops.

I assume there is something simple that I must be missing. I just want to see what the exit temperature of fluid will be given 60c fluid input temp and 30c ambient temp. I have been playing around with flow rates 2-5L/min.

Thanks for your help!!


Screenshot 2020-11-23 at 5.12.55 PM|690x334 !

Hi there!

I can see that you specified the initial temperature of the oil region to be 30°C. That explains why it starts low and then increases with time.

I would suggest to change this to the actual initial oil temperature of 60°C and compare the results.

Otherwise the setup seems ok to me.